Here are some of my thoughts on Frozen 2. I feel Frozen 2 is an allegory about indigenous land right disputes, environmentalism and democracy.
The dam which King Runeard built is said to have anger the four spirits dam. I believe the four elemental spirits are a metaphor of the nature. The building of the dam caused changes to the local microclimate. It is likely that the Enchanted Forest is quite up north, so it is quite cold. There is a lot of geothermal activities in the region. The geothermal activities heat up the lake and cause evaporation. The cold air cause the water vapour to condense, resulting a thick fog. Before the dam was built and the lake was formed, the lack of a large body of water probably meant that there was not much fog.
The fog prevented people from entering or leaving the Enchanted Forest. I believe it is a metaphor for the importance of having good outdoor navigation skills. It has been shown that people walk around in a circle when they cannot see the Sun[(Walking Straight into Circles, Current Biology Volume 19, Issue 18, 29 September 2009, Pages 1538-1542 https://www.sciencedirect.com/science/article/pii/S0960982209014791)]. Queen Elsa probably has superior navigational skills, that's probably why she managed to penetrate the fog. She was probably trained in navigation, as being the leader of a country probably require good geography skills, and she probably has to lead her army.
The rock giants are probably a metaphor of the dam-induced seismicities [(Dam–Induced Seismicity, excerpt from Silenced Rivers: The Ecology and Politics of Large Dams, by Patrick McCully, Zed Books, London, 1996 https://www.internationalrivers.org/dam%E2%80%93induced-seismicity)].
Later in the film, it was revealed that the dam was built to weaken the Northuldra people. I believe this is for teaching children about the conflict between land right dispute between indigenous people, which still happens today [(Construction of giant dam in Canada prompts human rights outcry, Guardian, https://www.theguardian.com/world/2016/aug/09/canada-site-c-hydroelectric-dam-indigenous-rights)].
The final destruction of the dam nearly caused Arendelle to flood. I believe it is inspired by Operation Chastise [(https://en.wikipedia.org/wiki/Operation_Chastise)], in which the Allies destroyed a German dam. The Arendelle is basically the Nazi Germany. The indigenous people are basically the Allies.
I believe Princess Anna's destruction of the dam was very irresponsible, as she did not perform an environmental impact study. Despite the fact that the dam was considered as harmful before destruction, there might be rare species living in the lake behind the damn. The spoils from the construction of Channel Tunnels has now formed a country park, with nationally rare plant species [(https://en.wikipedia.org/wiki/Samphire_Hoe_Country_Park)]. This could be the case for the lake behind the damn as well. Northuldra might have adapted their lifestyle to take advantage of the lake. A public consultation should have been conducted.
Finally the dam did not have to be destroyed immediately. The water-level could be gradually lowered. The catastrophic impact of dam destruction is also shown in the film. In the film, Queen Elsa had to use magical power to stop the flood. I think it is a metaphor of a political leader leading the effort of shoring up the levees, in the face of an imminent flooding. Dams are considered “installations containing dangerous forces” under International humanitarian law due to the massive impact of a possible destruction on the civilian population and the environment [(https://en.wikipedia.org/wiki/Dam_failure)]. If the flooding from the dam destroyed Arendelle, Princess Anna would have committed war crime against her own people. Therefore I believe Princess Anna needs to study Engineering.
Finally Queen Elsa abdicated to live in the Enchanted Forest. I believe it is in reference of King Edward VIII, who later became Duke of Windsor after his abdication [(https://en.wikipedia.org/wiki/Edward_VIII)]. I do not think abdication was necessary for Queen Elsa. She could have ruled over both Enchanted Forest by using a Personal Union [(https://en.wikipedia.org/wiki/Personal_union#United_Kingdom)], much like the British monarch. She is obviously not very good at statecraft. I therefore think that the now abdicated Queen Elsa needs to study Politics.
Overall, I think Frozen 2 is a very educational film. It has so many metaphors and hidden messages. It is good for teaching children about politics and environmentalism.